Electrochemical characterization of an aqueous lithium rechargeable battery: The effect of CeO2 additions to the MnO2 cathode
The effect of CeO2 additions on an aqueous rechargeable lithium battery has been investigated. The CeO2 additions (0, 2, and 5 wt.%)were made to the manganese dioxide (MnO2) cathode of a cell comprising zinc as an anode and an aqueous saturated lithium hydroxide solution as the electrolyte. The CeO2 enhances the performance of the cell in terms of capacity and resistance to capacity fade with cycling. This effect is only evident after the first charge cycle. The mechanism by which this occurs may be due to suppression of the oxygen evolution reaction during charging. This results in full reversion of the products of discharge (principally LixMnO2) to MnO2 during charging, and suppresses the formation of non-rechargeable oxyhydroxides. CeO2 additions of 2 wt.% were found to be most effective, since additions at the 5 wt.% level caused a decrease in capacity during long-term cycling. This could be due to a synchronizing effect. The effect of additions of a rare earth oxide (CeO2) and an alkaline earth oxide (CaO) on the electrochemical behavior of the cell is also compared and discussed.